diff --git a/src/libsystemd/sd-varlink/varlink-io.systemd.c b/src/libsystemd/sd-varlink/varlink-io.systemd.c
index 30c9495d40..cab64ef988 100644
--- a/src/libsystemd/sd-varlink/varlink-io.systemd.c
+++ b/src/libsystemd/sd-varlink/varlink-io.systemd.c
@@ -15,7 +15,7 @@ static SD_VARLINK_DEFINE_ERROR(
                 SD_VARLINK_FIELD_COMMENT("The Linux error name, i.e. ENOENT, EHWPOISON or similar."),
                 SD_VARLINK_DEFINE_FIELD(errnoName, SD_VARLINK_STRING, SD_VARLINK_NULLABLE),
                 SD_VARLINK_FIELD_COMMENT("The numeric Linux error number. Typically the name is preferable, if specified."),
-                SD_VARLINK_DEFINE_FIELD(errno, SD_VARLINK_STRING, SD_VARLINK_NULLABLE));
+                SD_VARLINK_DEFINE_FIELD(errno, SD_VARLINK_INT, SD_VARLINK_NULLABLE));
 
 SD_VARLINK_DEFINE_INTERFACE(
                 io_systemd,
diff --git a/src/login/logind-varlink.c b/src/login/logind-varlink.c
index a757033a55..23262fb9a5 100644
--- a/src/login/logind-varlink.c
+++ b/src/login/logind-varlink.c
@@ -133,8 +133,8 @@ int session_send_create_reply_varlink(Session *s, const sd_bus_error *error) {
                         SD_JSON_BUILD_PAIR_UNSIGNED("UID", s->user->user_record->uid),
                         SD_JSON_BUILD_PAIR_CONDITION(!!s->seat, "Seat", SD_JSON_BUILD_STRING(s->seat ? s->seat->id : NULL)),
                         SD_JSON_BUILD_PAIR_CONDITION(s->vtnr > 0, "VTNr", SD_JSON_BUILD_UNSIGNED(s->vtnr)),
-                        SD_JSON_BUILD_PAIR_STRING("Class", session_class_to_string(s->class)),
-                        SD_JSON_BUILD_PAIR_STRING("Type", session_type_to_string(s->type)));
+                        SD_JSON_BUILD_PAIR("Class", JSON_BUILD_STRING_UNDERSCORIFY(session_class_to_string(s->class))),
+                        SD_JSON_BUILD_PAIR("Type", JSON_BUILD_STRING_UNDERSCORIFY(session_type_to_string(s->type))));
 }
 
 static JSON_DISPATCH_ENUM_DEFINE(json_dispatch_session_class, SessionClass, session_class_from_string);